The broad objective of the proposed project is a detailed investigation of the properties of the recently detected DNA-polymerase in concentrated preparations of hepatitis associated antigen. In particular, the following questions will be examined: a) is the DNA- polymerase specific for Australia antigen positive hepatitis. b) can the polymerase serve as another laboratory parameter in the diagnosis of hepatitis. c) is the polymerase part of the putative hepatitis virus or is it also found in normal liver tissue. d) can the polymerase be used as a biochemical tag for the putative hepatitis virus. 3) is the DNA- polymerase truly a RNA-dependent DNA polymerase (reverse transcriptase). f) what are the biochemical properties of the polymerase. g) how does the HAA DNA-polymerase compare to the DNA polymerases of the avian and murine oncornaviruses. As part of the effort to answer these questions attempts will be made to develop reliable methods for the culture of hepatocytes and to pass the putative hepatitis virus in tissue culture. Bibliographic references: Hirschman, S.Z. DNA polymerase and hepatitis B antigen. J. Infect. Dis. 130:206-208, 1974. Hirschman, S. Z., Gerber, M., Garfinkel, E. Purification of naked intranuclear particles from human liver infected by hepatitis B virus. Proc. Nat. Acad. Sci. USA 71:3345-3349, 1974.